The Application of Multi-techniques for Joint Analysis of Rock in Case Investigation

The application of analysis of geological materials like rocks in forensic science is growing. It is of great significance to adopt multi-techniques for joint analysis.

This study employed X-ray diffraction (XRD) combined with Rietveld full spectrum fitting quantification, polarized light microscope (PLM), X-ray fluorescence spectrometry (XRF), and scanning electron microscope-energy dispersive spectrometry (SEM-EDS). These techniques were used to investigate the mineral and element composition of rock samples from crime scenes and suspects’ residence.

The study identified calcite altered by dolomitization, quartz, and illite in two samples. The main elements detected included magnesium, aluminum, silicon, phosphorus, sulfur, potassium, calcium, iron, and strontium. In the correlation calculation, the semi-quantitative data of minerals, oxides, and elements from two samples were set as index values, and the correlation coefficient between the samples was calculated. The coefficients were 0.999 by using the cosine of the angle and 0.965 by the Spearman’s rank correlation coefficient method.

The results suggested a probable common origin for the two rock samples. This study provides valuable tools and technical support for identifying geological materials such as rock, ore and solid waste in criminal investigation.